Motorcycle Repair: 2003 Big Bear, vacuum leak, intake tube

Question
Hi Mark.

Have a 2003 Big Bear with 400 single cylider engine. At idle is misses/backfires/dies. Acts a bit like vacuum leak on a car engine or carbon build up on a distributor cap. Seems fine at high RPM.

Emptied gas tank (including reserve) and replaced with fresh gas. Checked and adjusted carb/engine intake tube connection to eliminate leak. Checked other tubes to/from carb....OK. Checked plug...OK.

Your thoughts??

Answer
Hi Ivan,

Can you tell me if this ATV was stored or not started for several days or weeks?

Will the engine start and run, or run better with the choke applied?

Describe the appearance of the spark plug. Any additional history of repairs or other details is helpful. Reply and we'll go from there.

Please include your email address as requested and explained in my instructions. For our convenience, I return tech information files by email.

Respectfully,
Mark Shively